Certain microorganisms are produced in large quantities and can be formulated for various commercial uses. For example, microbial products have been used in agriculture to protect plants from pests and diseases, to improve plant performance and nutrition, and as inoculants for silages. These microbial products must be produced in a way that is efficient, free of contamination, and suitable for maintaining high levels of viable microorganisms. Production of microbial formulations for commercial use requires drying the microorganisms in a way that preserves viability of the microbes, provides a suitable medium for commercial use, and maintains an extended shelf life of the microbial product.
A range of microorganisms have been produced and formulated for commercial use. Examples of commercially formulated microorganisms include strains of Lactobacillus spp. for a variety of food, probiotic, and animal feed uses; entomophagous fungi, such as Beaveria and Metarhizum spp., for control of plant-attacking insects; fungi that protect plants from diseases, such as Trichoderma and Clonostachys spp.; bacteria that protect plants from disease, such as Pseudomonas and Bacillus spp., as well as Rhizobium and Bradyrhizobium; and related bacteria that fix nitrogen through a symbiotic relationship with legumes and fungi, such as Colletotrichum spp., which are used as weed controls by causing disease in weeds.
Peat-based inoculants presently constitute the vast majority of inoculants marketed today, and their development is primarily due to their convenience in holding and distributing desired microorganisms. In the known art, such soil-like compositions are required in order to provide a substrate and a food source for the microorganisms in the interim period before the microbial products are applied to such materials as seed or plants. For example, in order to maintain high levels of viable microorganisms, useful microbial products relating to inoculants such as Rhizobium have typically been packaged in a peat medium or other humus-type carrier.
Many times peat requires processing before it may serve as a carrier medium for desired microorganisms. For example, at least one U.S. patent describes a typical process in which pH adjusted sedge peat is oven dried and milled in a hammer mill before being passed through a sieve. The powdered peat is sealed into polyethene bags and sterilized by gamma radiation. All of this occurs before sterilized packs are then injected with the desired microorganisms. Post injection, the injection hole is then re-sealed to prevent contamination.
The use of peat or other humus-type materials is problematic as a carrier medium. First, peat and many other humus-type carrier materials in the known art are abrasive. Planting equipment and many other types of equipment may be sensitive to the added friction introduced by the presence of peat in the formulation. Therefore, when peat based inoculants are applied to the seed, these formulations may actually increase the friction in the planting equipment (or other industrial equipment which may be used). Peat-based inoculants may tend to increase seed binding and bridging in planter hoppers, and additionally, may increase the wear and tear on critical metering parts and equipment.
Although humus-type materials can sustain desired microbes for extended periods, these compositions may be equally suitable for promoting the growth of contaminate species. These species may negatively affect the performance of the desired microorganisms. Although sterilizing the peat may provide a contaminate-free starting point, contaminate species may ultimately infiltrate and affect the performance of the inoculants.
Accordingly, new and improved methods of producing microbial products that are machine friendly, resistant to contaminate microorganisms, and which continue to have high activity levels and an extended shelf life are needed. Exemplary embodiments are directed to overcoming these and other limitations in the art.